cg and opengl

I’m try to create and compile cg shader from fx composer , but i have some problem , then i pass to compile with cgc.
What are the specific?
1)I must call my shader only “main” for the fragment or vertex shader?
2)i must separate the vertex and the fragment shader?
3)if i separate the vertex and fragment shader how i can send values for ex from the vshader to the fragment shader? is automatically?
4)how i can access light created in opengl?is possible?
5)how is better declare the constans vars in cg in a struct?

So what are you posting here for? This is a GLSL forum.

Try’s Cg Forum